In the world of communication, there are many methods to communicate over a network. Among these methods of communication is Push-to-talk (PTT). PTT is a narrowband service that allows a user to communicate over a channel merely by pressing and holding a PTT button on a communication device.
One particular version of PTT, called PoC (PTT-over-Cellular), has been implemented in networks such as Global Systems for Mobile Communications (GSM)/General Packet Radio Service (GPRS) and Code Division Multiple Access (CDMA) cellular networks. By using internet protocols (IP), these networks can provide a packet-based data service that enables information to be sent and received across a mobile telephone network. In addition, the use of internet protocols also facilitates PoC through the use of substantially instant connections. That is, information can be sent or received substantially immediately as the need arises, subject to availability of resources in the air interface.
When extending narrowband services over IP networks, Session Initiation Protocol (SIP) is used for call control due to its wide acceptance. However, the use of SIP can impact performance since the SIP messages are typically very large, and a three-way handshake is required. These are serious drawbacks, for example, when extending a Project 25 (P25) group call (e.g., for public safety applications) over an IP network due to high performance expectations for these types of calls. Some mechanisms are available for pre-establishing a session prior to a call (wherein media is transmitted) in an attempt to avoid the delay inherent in establishing a session. However, these mechanisms do not provide sufficient flexibility and can waste valuable RF resources.
Accordingly, there is a need for a method and an apparatus for enabling group communication.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of various embodiments. In addition, the description and drawings do not necessarily require the order illustrated. It will be further appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required.
Apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the various embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Thus, it will be appreciated that for simplicity and clarity of illustration, common and well-understood elements that are useful or necessary in a commercially feasible embodiment may not be depicted in order to facilitate a less obstructed view of these various embodiments.